DRAFT: Single widget manager per kernel

.github/workflows/packaging.yml

@@ -134,7 +134,7 @@ jobs:
       - name: Check the JupyterLab extension is installed
         if: matrix.dist != 'widgetsnbextension*.tar.gz'
         run: |
-          python -m pip install jupyterlab~=3.0
+          python -m pip install jupyterlab~=4.0
 
           jupyter labextension list
           jupyter labextension list 2>&1 | grep -ie "@jupyter-widgets/jupyterlab-manager.*enabled.*ok" -

packages/base-manager/src/manager-base.ts

@@ -214,10 +214,14 @@ export abstract class ManagerBase implements IWidgetManager {
    *
    * If you would like to synchronously test if a model exists, use .has_model().
    */
-  async get_model(model_id: string): Promise<WidgetModel> {
+  async get_model(model_id: string, delays = [500]): Promise<WidgetModel> {
+    let i = 0;
+    while (!this._models[model_id] && i < delays.length) {
+      await new Promise((resolve) => setTimeout(resolve, delays[i++]));
+    }
     const modelPromise = this._models[model_id];
     if (modelPromise === undefined) {
-      throw new Error('widget model not found');
+      throw new Error(`widget model '${model_id}' not found`);
     }
     return modelPromise;
   }
@@ -383,15 +387,21 @@ export abstract class ManagerBase implements IWidgetManager {
     // Try fetching all widget states through the control comm
     let data: any;
     let buffers: any;
+    let timeoutID: number | undefined;
+    const comm_ids = await this._get_comm_info();
+    if (Object.keys(comm_ids).length === 0) {
+      // There is nothing to load, either a new kernel or no widgets in the kernel.
+      return Promise.resolve();
+    }
     try {
       const initComm = await this._create_comm(
         CONTROL_COMM_TARGET,
         uuid(),
         {},
         { version: CONTROL_COMM_PROTOCOL_VERSION }
       );
-
       await new Promise((resolve, reject) => {
+        let succeeded = false;
         initComm.on_msg((msg: any) => {
           data = msg['content']['data'];
 
@@ -409,22 +419,24 @@ export abstract class ManagerBase implements IWidgetManager {
               return new DataView(b instanceof ArrayBuffer ? b : b.buffer);
             }
           });
-
+          succeeded = true;
+          clearTimeout(timeoutID);
           resolve(null);
         });
 
-        initComm.on_close(() => reject('Control comm was closed too early'));
+        initComm.on_close(() => {
+          if (!succeeded) reject('Control comm was closed too early');
+        });
 
         // Send a states request msg
         initComm.send({ method: 'request_states' }, {});
 
         // Reject if we didn't get a response in time
-        setTimeout(
+        timeoutID = window.setTimeout(
           () => reject('Control comm did not respond in time'),
           CONTROL_COMM_TIMEOUT
         );
       });
-
       initComm.close();
     } catch (error) {
       // Fall back to the old implementation for old ipywidgets backend versions (ipywidgets<=7.6)
@@ -487,6 +499,9 @@ export abstract class ManagerBase implements IWidgetManager {
               model.constructor as typeof WidgetModel
             )._deserialize_state(state.state, this);
             model!.set_state(deserializedState);
+            if (!model.comm_live) {
+              model.comm = await this._create_comm('jupyter.widget', widget_id);
+            }
           }
         } catch (error) {
           // Failed to create a widget model, we continue creating other models so that
@@ -738,12 +753,12 @@ export abstract class ManagerBase implements IWidgetManager {
 
   /**
    * Disconnect the widget manager from the kernel, setting each model's comm
-   * as dead.
+   * as undefined.
    */
   disconnect(): void {
     Object.keys(this._models).forEach((i) => {
       this._models[i].then((model) => {
-        model.comm_live = false;
+        model.comm = undefined;
       });
     });
   }

packages/base/src/errorwidget.ts

@@ -24,7 +24,9 @@ export function createErrorWidgetModel(
         error: error,
       };
       super(attributes, options);
-      this.comm_live = true;
+    }
+    get comm_live(): boolean {
+      return true;
     }
   }
   return ErrorWidget;

packages/base/src/widget.ts

@@ -160,7 +160,7 @@ export class WidgetModel extends Backbone.Model {
     // Attributes should be initialized here, since user initialization may depend on it
     this.widget_manager = options.widget_manager;
     this.model_id = options.model_id;
-    const comm = options.comm;
+    this.comm = options.comm;
 
     this.views = Object.create(null);
     this.state_change = Promise.resolve();
@@ -174,27 +174,23 @@ export class WidgetModel extends Backbone.Model {
     // _buffered_state_diff must be created *after* the super.initialize
     // call above. See the note in the set() method below.
     this._buffered_state_diff = {};
+  }
 
-    if (comm) {
-      // Remember comm associated with the model.
-      this.comm = comm;
+  get comm() {
+    return this._comm;
+  }
 
-      // Hook comm messages up to model.
+  set comm(comm: IClassicComm | undefined) {
+    this._comm = comm;
+    if (comm) {
       comm.on_close(this._handle_comm_closed.bind(this));
       comm.on_msg(this._handle_comm_msg.bind(this));
-
-      this.comm_live = true;
-    } else {
-      this.comm_live = false;
     }
+    this.trigger('comm_live_update');
   }
 
-  get comm_live(): boolean {
-    return this._comm_live;
-  }
-  set comm_live(x) {
-    this._comm_live = x;
-    this.trigger('comm_live_update');
+  get comm_live() {
+    return Boolean(this.comm);
   }
 
   /**
@@ -218,39 +214,46 @@ export class WidgetModel extends Backbone.Model {
    *
    * @returns - a promise that is fulfilled when all the associated views have been removed.
    */
-  close(comm_closed = false): Promise<void> {
+  async close(comm_closed = false): Promise<void> {
     // can only be closed once.
     if (this._closed) {
-      return Promise.resolve();
+      return;
     }
     this._closed = true;
-    if (this.comm && !comm_closed) {
-      this.comm.close();
+    if (this._comm && !comm_closed) {
+      try {
+        this._comm.close();
+      } catch (err) {
+        // Do Nothing
+      }
     }
     this.stopListening();
     this.trigger('destroy', this);
-    if (this.comm) {
-      delete this.comm;
-    }
+    delete this._comm;
+
     // Delete all views of this model
     if (this.views) {
       const views = Object.keys(this.views).map((id: string) => {
         return this.views![id].then((view) => view.remove());
       });
       delete this.views;
-      return Promise.all(views).then(() => {
-        return;
-      });
+      await Promise.all(views);
+      return;
     }
-    return Promise.resolve();
   }
 
   /**
    * Handle when a widget comm is closed.
    */
   _handle_comm_closed(msg: KernelMessage.ICommCloseMsg): void {
+    if (!this.comm) {
+      return;
+    }
+    this.comm = undefined;
     this.trigger('comm:close');
-    this.close(true);
+    if (!this._closed) {
+      this.close(true);
+    }
   }
 
   /**
@@ -635,7 +638,7 @@ export class WidgetModel extends Backbone.Model {
    * This invokes a Backbone.Sync.
    */
   save_changes(callbacks?: {}): void {
-    if (this.comm_live) {
+    if (this.comm) {
       const options: any = { patch: true };
       if (callbacks) {
         options.callbacks = callbacks;
@@ -721,11 +724,9 @@ export class WidgetModel extends Backbone.Model {
   model_id: string;
   views?: { [key: string]: Promise<WidgetView> };
   state_change: Promise<any>;
-  comm?: IClassicComm;
   name: string;
   module: string;
-
-  private _comm_live: boolean;
+  private _comm?: IClassicComm;
   private _closed: boolean;
   private _state_lock: any;
   private _buffered_state_diff: any;

packages/base/test/src/widget_test.ts

@@ -194,15 +194,15 @@ describe('WidgetModel', function () {
       });
     });
 
-    it('sets the widget_manager, id, comm, and comm_live properties', function () {
-      const widgetDead = new WidgetModel({}, {
-        model_id: 'widgetDead',
+    it('sets the widget_manager, id, comm, properties', function () {
+      const widgetNoComm = new WidgetModel({}, {
+        model_id: 'noComm',
         widget_manager: this.manager,
       } as IBackboneModelOptions);
-      expect(widgetDead.model_id).to.equal('widgetDead');
-      expect(widgetDead.widget_manager).to.equal(this.manager);
-      expect(widgetDead.comm).to.be.undefined;
-      expect(widgetDead.comm_live).to.be.false;
+      expect(widgetNoComm.model_id).to.equal('noComm');
+      expect(widgetNoComm.widget_manager).to.equal(this.manager);
+      expect(widgetNoComm.comm).to.be.undefined;
+      expect(widgetNoComm.comm_live).to.be.false;
 
       const comm = new MockComm();
       const widgetLive = new WidgetModel({}, {

packages/controls/css/widgets-base.css

@@ -125,6 +125,18 @@
   flex-direction: column;
 }
 
+.jupyter-widget-output {
+  box-sizing: border-box;
+  display: flex;
+  margin: 0;
+  overflow: auto;
+  flex-direction: column;
+}
+.jupyter-widget-output .jp-OutputArea-prompt{
+  width: 0;
+  flex : 0;
+}
+
 /* General Tags Styling */
 
 .jupyter-widget-tagsinput {

python/jupyterlab_widgets/package.json

@@ -51,13 +51,13 @@
     "@jupyter-widgets/controls": "^5.0.11",
     "@jupyter-widgets/output": "^6.0.10",
     "@jupyterlab/application": "^3.0.0 || ^4.0.0",
-    "@jupyterlab/apputils": "^3.0.0 || ^4.0.0",
     "@jupyterlab/console": "^3.0.0 || ^4.0.0",
     "@jupyterlab/docregistry": "^3.0.0 || ^4.0.0",
     "@jupyterlab/logconsole": "^3.0.0 || ^4.0.0",
     "@jupyterlab/mainmenu": "^3.0.0 || ^4.0.0",
     "@jupyterlab/nbformat": "^3.0.0 || ^4.0.0",
     "@jupyterlab/notebook": "^3.0.0 || ^4.0.0",
+    "@jupyterlab/observables": "^5.2.1",
     "@jupyterlab/outputarea": "^3.0.0 || ^4.0.0",
     "@jupyterlab/rendermime": "^3.0.0 || ^4.0.0",
     "@jupyterlab/rendermime-interfaces": "^3.0.0 || ^4.0.0",
@@ -75,7 +75,6 @@
   },
   "devDependencies": {
     "@jupyterlab/builder": "^3.0.0 || ^4.0.0",
-    "@jupyterlab/cells": "^3.0.0 || ^4.0.0",
     "@types/jquery": "^3.5.16",
     "@types/semver": "^7.3.6",
     "@typescript-eslint/eslint-plugin": "^5.8.0",

python/jupyterlab_widgets/src/index.ts

@@ -8,11 +8,7 @@ export default WidgetManagerProvider;
 
 export { registerWidgetManager } from './plugin';
 
-export {
-  KernelWidgetManager,
-  LabWidgetManager,
-  WidgetManager,
-} from './manager';
+export { KernelWidgetManager, WidgetManager } from './manager';
 
 export { WidgetRenderer } from './renderer';